Hand-Held Surface Profiler With Fixed Baseline Triangulation
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Solution Overview
Problem
Existing light-emitting surface profilers face inaccuracies and limitations in scanning both interior and exterior surfaces due to baseline shifts, angle variations, and the difficulty in accessing small or enclosed objects, which affects their accuracy and usability.
Innovation Solution
A compact, hand-held surface profiler with a focusable laser module and a camera system housed in a rigid, transparent cylindrical structure, where the laser and camera are positionally referentially coupled to maintain a fixed baseline and angle, allowing for accurate triangulation and scanning of surfaces with a disc-shaped or cone-shaped scanning beam, and utilizing calibration targets to determine precise location points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a moveable arm with encoders is used to position the laser scanner and camera, then the system can scan surfaces from multiple points of view, but the size of the moveable arm, scanner and camera prevents scanning of small object interiors
Solution Approach 1:
The system is segmented into a compact handheld scanner unit and a separate control/computing unit. The scanner contains only the essential components (laser, camera, optics) in a miniaturized configuration, while the moveable arm and encoders are eliminated entirely in favor of a portable design that can be manually positioned.
Solution Approach 2:
The mechanical positioning system (moveable arm with encoders) is replaced by a handheld portable scanner that relies on manual positioning and digital calibration. The mechanical complexity is substituted with a simpler portable design that uses software-based coordinate mapping instead of hardware-based positional tracking.
2Ease of operation
If the laser and camera are mounted on a stalk that oscillates or moves, then the system can access enclosed spaces, but accurate scanning measurements become difficult to obtain
Solution Approach 1:
The system performs preliminary calibration by projecting the laser line onto a calibration target at multiple known positions and orientations before actual scanning. This pre-establishes the geometric relationship between laser and camera, creating a reference framework that compensates for any subsequent movements or oscillations during scanning.
Solution Approach 2:
The system uses feedback from the calibration process to dynamically adjust and maintain accurate measurements. The calibration data provides continuous reference information that allows the system to compensate for positional changes and maintain measurement precision even when the handheld scanner moves during operation.
3Measurement precision
If the baseline distance between laser and camera is fixed, then triangulation accuracy is maintained, but the system cannot adapt to different scanning scenarios
Solution Approach 1:
The system changes the parameter of baseline distance from a fixed physical constraint to a variable that can be optically adjusted. The focusable laser module allows the effective baseline (optical path difference) to be varied by changing the focal plane position, enabling the same physical baseline to serve multiple scanning scenarios with different depth ranges and resolutions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides accurate and stable scanning capabilities for a wide range of surface shapes and sizes, including small objects, by maintaining a constant baseline and angle, and allows for precise measurement and profiling of both interior and exterior surfaces with improved accuracy and ease of use.
Implementation Method 1
Light emitted by the laser is incident on a target surface and imaged onto a camera by a lens positioned behind the laser
Implementation Method 2
Camera 14 incorporates an imaging sensor 16 for detecting light and a lens 15 for focusing and imaging light onto imaging sensor 16
Implementation Method 3
The relationship between locations on the surface of an object and locations on imaging sensor 16 is determined by the physical arrangement of laser 12 and camera 14. In particular, the distance between laser 12 and camera 14 (i.e. baseline 20) is fixed, as well as the angle θ between laser beam 18 and baseline 20
Data Source
AI summary
A light-emitting hand-held surface profiler for scanning and profiling the surfaces of objects has a transparent housing, a focusable light source, a conical mirror aligned to redirect light emitted by the light source onto a surface to be profiled, an imaging sensor and a lens aligned to redirect toward the imaging sensor light reflected by the surface onto the lens. The light source, conical mirror, imaging sensor and lens are mounted within the housing and positionally referentially coupled to the housing.